preinst is in grub-legacy-ec2 1:1.
This file is a maintainer script. It is executed when installing (*inst) or removing (*rm) the package.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 | #!/bin/sh
set -e
if [ "$1" = "install" -o "$1" = "upgrade" ]; then
dpkg-divert --package grub-legacy-ec2 --rename --divert \
/usr/sbin/grub-set-default.real --add /usr/sbin/grub-set-default
fi
|